Question

1 a-2a-{3a-(4a-5)} i need help plz and on this one to 13(5-t)-(5-t)-12(5-t)

Answer 1

13(5-t)-(5-t)-12(5-t)
=65-13t-5-t-60+12t
=-13t-t+12t+65-5-60
=-2t

a-2a-{3a-(4a-5)}
=a-2a-3a-4a-5
=-8a-5